%I #6 Oct 31 2013 12:17:43
%S 4,6,1,9,7,7,6,8,9,0,3,3,0,3,6,8,9,3,8,0,6,8,2,1,1,9,9,6,8,4,3,7,4,2,
%T 3,8,4,0,1,7,2,8,2,5,5,6,4,4,1,2,9,2,3,3,8,9,8,4,2,0,8,2,3,2,9,6,3,7,
%U 4,4,6,3,0,8,4,4,2,5,9,6,4,4,8,6,7,2,8,7,1,8,8,0,3,1,6,6,5,0,8,2,3,6,4,2,8
%N Decimal expansion of the continued fraction 4+6/(9+10/(14+15/21+...)) where the terms are the semiprimes: A001358.
%e 4.6197768903303689380682119968437423840172825564412923389842082329...
%t semiPrimeQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; lst = Select[Range@ 400, semiPrimeQ@ # &]; First@ RealDigits@ N[ Fold[ Last@ #2 + First@ #2/#1 &, 4, Partition[Reverse@ lst, 2]], 111] (* _Robert G. Wilson v_ *)
%Y Cf. A001358, A113011.
%K cons,nonn
%O 1,1
%A _Jonathan Vos Post_ & _Robert G. Wilson v_, Sep 08 2007